"Alex is the sweetest person ever," Mark Lewis, a friend, told the publication. "After the explosion we haven't heard from them. We tried all hospitals with no luck. Their mom was the last to speak to them, but their call was cut off after the explosion."

On social media, friends and family of the siblings are asking for any help in locating them.

We are still looking for Alexander Pinczowski and his sister Sascha. They are missing in the Brussels airport attack...